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West Pacific/2015/09W/Archive/28
Public advisory TYPHOON CHAN-HOM PUBLIC ADVISORY NUMBER 28 WIKI-HURRICANES FORECASTING CENTER 6:00 AM JST TUE JUL 07 2015 ...TYPHOON CHAN-HOM CONTINUES TO ORGANIZE... ...LIKELY TO BECOME A POWERFUL CYCLONE IN THE COMING DAYS... SUMMARY OF 6:00 AM JST...21:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...18.1N 137.9E CENTER POSITION CONFIDENCE: HIGH ABOUT 565 MI...910 KM WNW OF SAIPAN, MARIANA ISLANDS MAXIMUM SUSTAINED WINDS...75 KT...85 MPH...140 KM/H MINIMUM BAROMETRIC PRESSURE...969 MB...28.62 INCHES PRESENT MOVEMENT...WNW AT 10 KT...12 MPH...19 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 6:00 am JST, the center of Typhoon Chan-hom was situated near 18.1N 137.9E, about 565 miles (910 km) west-northwest of Saipan, Mariana Islands. Maximum sustained winds were 75 knots (85 mph, 140 km/h), with higher gusts. The minimum barometric pressure was 969 millibars (hPa; 29.62 inHg), and the cyclone was tracking west-northwest at 10 knots (12 mph, 19 km/h). Environmental conditions are expected to favor steady to rapid intensification over the next 48 hours, and Chan-hom is likely to become a powerful cyclone over the West Pacific. NEXT ADVISORY ------------------- Next complete advisory at 12:00 pm JST. $$ Forecaster TAWX14 Discussion TYPHOON CHAN-HOM DISCUSSION NUMBER 28 WIKI-HURRICANES FORECASTING CENTER 6:00 AM JST TUE JUL 07 2015 Typhoon Chan-hom has continued to organize since the previous advisory. Deep convection has increased near the center, the spiral band wrapping into the center from the east has continued to become better defined, and upper-level outflow continues to be excellent in all quadrants, especially to the north as a poleward outflow channel finally becomes established. Recent satellite intensity estimates were T4.0/65kt from JTWC, T4.5/77kt from SAB, and T4.4/74.6kt from UW-CIMSS ADT. A blend of these data supports raising the initial intensity to 75kt. Chan-hom has continued its west-northwest motion this afternoon, and there is very little reason to believe this trajectory will change over the coming days. The cyclone continues to be steered by a strong mid-level ridge across the northern West Pacific. On the current trajectory, Chan-hom is expected to approach the southernmost Japanese Islands in 72 hours or so before moving into the China mainland between days 4 and 5. Given the forecast intensity, Chan-hom poses an extreme threat to the aforementioned locations, and residents there should prepare for life-threatening conditions. As mentioned previously, the upper-level setup for Chan-hom has continued to improve with the establishment of a poleward outflow channel. Over the coming days, low wind shear coupled with sea surface temperatures near 31C and ocean heat content above 75 kJ/cm^2 is expected to favor steady to rapid intensification. The only identifiable negating factor is the presence of mid-level dry air wrapping in from the west of the cyclone. However, if Chan-hom can solidify an inner core and mix out what dry air still remains in the center, then this factor should be negligible at best. The updated forecast indicates Chan-hom to reach Category 3 status within 24 hours and further intensify to Category 5 status by 72 hours, if not sooner. It is worth noting that the structural changes within the inner cores of powerful cyclones are not well forecast, and such changes could ultimately influence the peak of Chan-hom. INIT 06/2100Z 18.1N 137.9E 75 KT 85 MPH 12H 07/0600Z 18.7N 136.1E 85 KT 100 MPH 24H 07/1800Z 19.5N 134.1E 105 KT 120 MPH 36H 08/0600Z 20.6N 131.9E 120 KT 140 MPH 48H 08/1800Z 22.2N 129.8E 130 KT 150 MPH 72H 09/1800Z 24.8N 125.3E 140 KT 160 MPH...NEAR SOUTHERNMOST JAPANESE ISLANDS 96H 10/1800Z 27.2N 121.1E 130 KT 150 MPH...APPROACHING CHINA 120H 11/1800Z 29.4N 118.7E 50 KT 60 MPH...INLAND $$ Forecaster TAWX14